Eating 400 calories a day from these foods could raise dementia risk by over 20%

A team of researchers from the University of São Paulo Medical School in Brazil followed a diverse sample of more than 10,000 Brazilians for up to 10 years. The subjects filled out food frequency questionnaires to note how often they were eating foods including: unprocessed or minimally processed ingredients (aka whole foods like fresh, dry or frozen fruits, vegetables, whole grains, meat, fish and milk that underwent minimal processing, like pasteurization); processed foods (canned fruits, artisanal bread and cheese, and salted, smoked or cured meat or fish); and ultra-processed foods (industrial formulations of processed food substances like oils, fats, sugars, starch, artificial flavors and colorings, but containing little or no whole foods). 

The subjects also took cognitive tests up to three times a year, including memory tests and word recognition tests, to monitor their cognitive functioning; aka, mental abilities such as learning, thinking, reasoning, remembering, problem-solving, decision-making and attention. They also took regular verbal fluency tests to track their executive functioning; aka the mental skills that help an individual plan, monitor and successfully meet their goals. 

The findings? Those who ate 20% or more of their daily calories from ultra-processed foods had a 28% faster rate of cognitive decline, and a 25% faster rate of executive function decline, compared to the subjects in the study who ate the least amount of processed foods. In other words, someone following a 2,000-calorie-a-day diet who consumed 400 of their daily calories from ready-to-eat frozen meals, processed meats, breakfast cereals and sugar-sweetened beverages each day saw a faster rate of cognitive decline. 

Opinion: Your diet isn’t just making you obese, it could be speeding up cognitive decline

And many of us are fueling ourselves with these ultra-processed foods. The researchers noted that a whopping 58% of the calories consumed by U.S. citizens come from ultra-processed foods. We’re not alone; 56.8% of the calories consumed by British citizens, 48% of the calories consumed by Canadians, and up to 30% of the calories eaten by Brazilians also typically come from these ultra-processed foods, the researchers added. And despite the rise in plant-based alternatives (some of which are highly processed, themselves) and poultry consumption — and a dip in buying and eating unprocessed red meat — another recent report noted that Americans are still eating as much processed food as they did two decades ago, particularly deli meats, sausage, hot dogs, ham and bacon.

Related: Putting less sugar in packaged foods could prevent millions of Americans from getting sick — and save the U.S. over $160 billion

But there was an interesting catch in the cognitive decline study: If the overall quality of a subject’s diet was otherwise very high (meaning they ate a lot of unprocessed whole foods like fruits and vegetables, whole grains and lean proteins), then this association between ultra-processed foods and dementia disappeared. So the good news is, you can counter consuming these often cheap and easily-accessible ultra-processed foods by cooking more at home (which can also save you money) and preparing your food with whole foods like fresh or frozen produce, whole grains and lean meats and proteins. 

“Limiting ultra-processed food consumption, particularly in middle-aged adults, may be an efficient form to prevent cognitive decline,” the researchers wrote in their findings published in the journal JAMA Neurology this week. Indeed, this aligns with what health officials such as the American Heart Association have been saying: rather than calling out “good” or “bad” individual foods, folks should focus on eating an overall healthy diet that is high in fruits and vegetables, whole grains and lean/high-fiber proteins that are minimally processed. 

Read more: No more ‘good’ vs. ‘bad’ foods: 10 healthy eating ‘patterns’ to prevent heart disease and death

But brain health isn’t the only concern when it comes to ultra-processed foods. Here are four other ways that these ready-made meals and snacks can hurt your health. 

Processed foods raise your risk of heart disease

An analysis of almost 30,000 people published in the JAMA Internal Medicine journal in 2020 suggested that eating two servings of red meat and processed meat each week – such as two hot dogs or four pieces of bacon – was…